Sighting in Fay-le-Clos, March 29, 1980

Four witnesses travelling in two cars saw a circular luminous phenomenon moving across the sky toward the west. Witnesses described it as a very bright ball, phosphorescent white, orange or red depending on the person, with "green reflections" shaped like "feet". Once they had all gathered at the same spot, they kept watching until it vanished behind the mountains to the northwest. Depending on the witness, the observation lasted between 5 and 20 minutes.

The investigation concluded that it was very probably Venus. The long duration is typical of confusion with a celestial body. The direction (northwest or west) and low height in the sky match Venus's position at those times, about 6° above the horizon, in the west-northwest. The most common description, white, point-like and very bright, fits this hypothesis. Because Venus was so close to the horizon, atmospheric turbulence could briefly alter its brightness, produce short colour changes (red, green) and cause strong flashes, which the witnesses took for "luminous feet". The apparent fast movement is explained by the cars' motion: the unrecognised star seemed to follow the witnesses. When the witnesses were stationary, a drop in brightness caused by the thickness of the atmosphere could be read as the object moving away. The slow movement matches Venus setting, and its disappearance matches Venus passing behind the Forez mountains.

Only a cloud layer hiding Venus could have undermined this explanation. However, the only data available indicated a mostly clear sky (2/8) at 35 km, so the likelihood of another phenomenon is very low. GEIPAN classed the case as A: very probable observation of the planet Venus. The case, first classed D, was reexamined using new tools and experience gained since.